1. Technical Field
The embodiments described herein relate to an apparatus for transmitting a signal in a semiconductor integrated circuit, and more particularly, to an apparatus for transmitting a signal in a semiconductor integrated circuit that is capable of adjusting a multilevel transmission operation, an operation speed, and a swing level of an output signal.
2. Related Art
In recent years, the operation speed, integration level, and capacity have been increasing for conventional semiconductor integrated circuits. In order to achieve these advances in conventional semiconductor integrated circuits, a variety of new technologies have been used. For example, a multilevel transmission technology is widely used as an information transmission technology. In a multilevel transmitting apparatus, information of a plurality of bits may be transmitted via a single transmission bit. The information that is transmitted using a plurality of bits is decoded from the single transmission bit, which can be transmitted at any signal level.
That is, unlike traditional data transmission schemes where a single bit represent one of two discrete signal levels including a high level and a low level, in a multilevel transmission system, a plurality of signal levels, for example, four levels are included in data of one bit, and then the data is transmitted. Accordingly, multilevel transmission systems can achieve an improved information transmission speed.
Further, the operation speed of a semiconductor integrated circuit can be improved by implementing a technology that utilizes a high frequency clock. However, the use of a high frequency increases power consumption in the semiconductor integrated circuit.
In general, a semiconductor integrated circuit includes a signal transmitting apparatus and transmits an output signal through an external channel. At this time, as described above, if the operation speed of the signal transmitting apparatus is increased, it becomes difficult to decrease power consumption. If power consumption is decreased, it becomes difficult to increase the operation speed of the signal transmitting apparatus. Preferably, the signal transmitting apparatus selectively performs operations at a high speed or with low power according to required conditions in the signal transmitting apparatus. However, it is difficult to achieve a signal transmitting apparatus that can selectively adjust to the predetermined conditions according to given situations.